To improve therapeutic outcomes in children, it is necessary to conduct well-designed clinical research under the guidance of experts in a safe and ethical environment. The overall objective of clinical research in children is to develop and evaluate new treatments for pediatric diseases, disseminate the knowledge gained from the research, and encourage a culture in which this new knowledge is used to promote evidence-based medical care delivered by well-informed, competent providers. To meet this challenge, the overall objective of the proposed Pediatric Pharmacology Research Unit (PPRU) at the Arkansas Children's Hospital (ACM) is to join with other experts in pediatric clinical pharmacology to form a multi-center, collaborative network whose primary purposes are to: (1) to design, implement, and complete clinical studies of new and already marketed drugs, with the ultimate goal of expanding the drug label to include dosing and safety information specific to the pediatric population; (2) to conduct translational and clinical research designed to define the developmental characteristics of drug metabolism, elimination, and action, accounting for individual Variation based on genotype and phenotype; (3) to develop novel approaches and methods designed to improve the quality and value of the knowledge gained from therapeutic research; and (4) to train health care professionals in clinical and developmental pharmacology. To accomplish these objectives, an organizational structure supporting functional units designed to meet each of these objectives is in place. The PPRU at ACH operates under a detailed set of standard operating procedures, with quality assurance and continuous quality improvement activities, to provide a safe, ethical environment designed to protect children as they participate in critical pediatric research projects. Specific research proposals offered in this application were developed to examine significant therapeutic and safety questions arising from two common pediatric diseases, asthma and attention deficit hyperactivity disorder (ADHD). A well-defined program to educate students as well as experienced health care providers is in place. Ultimately, the primary mission of the PPRU Network, to improve pediatric therapeutics.